/*
 * Copyright (c) 1994, 2003, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
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 *
 *
 *
 *
 *
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 */

package java.io;

/**
 * The class implements a buffered output stream. By setting up such
 * an output stream, an application can write bytes to the underlying
 * output stream without necessarily causing a call to the underlying
 * system for each byte written.
 *
 * @author Arthur van Hoff
 * @since JDK1.0
 */
public class BufferedOutputStream extends FilterOutputStream {

  /**
   * The internal buffer where data is stored.
   */
  protected byte buf[];

  /**
   * The number of valid bytes in the buffer. This value is always
   * in the range <tt>0</tt> through <tt>buf.length</tt>; elements
   * <tt>buf[0]</tt> through <tt>buf[count-1]</tt> contain valid
   * byte data.
   */
  protected int count;

  /**
   * Creates a new buffered output stream to write data to the
   * specified underlying output stream.
   *
   * @param out the underlying output stream.
   */
  public BufferedOutputStream(OutputStream out) {
    this(out, 8192);
  }

  /**
   * Creates a new buffered output stream to write data to the
   * specified underlying output stream with the specified buffer
   * size.
   *
   * @param out the underlying output stream.
   * @param size the buffer size.
   * @throws IllegalArgumentException if size &lt;= 0.
   */
  public BufferedOutputStream(OutputStream out, int size) {
    super(out);
    if (size <= 0) {
      throw new IllegalArgumentException("Buffer size <= 0");
    }
    buf = new byte[size];
  }

  /**
   * Flush the internal buffer
   */
  private void flushBuffer() throws IOException {
    if (count > 0) {
      out.write(buf, 0, count);
      count = 0;
    }
  }

  /**
   * Writes the specified byte to this buffered output stream.
   *
   * @param b the byte to be written.
   * @throws IOException if an I/O error occurs.
   */
  public synchronized void write(int b) throws IOException {
    if (count >= buf.length) {
      flushBuffer();
    }
    buf[count++] = (byte) b;
  }

  /**
   * Writes <code>len</code> bytes from the specified byte array
   * starting at offset <code>off</code> to this buffered output stream.
   *
   * <p> Ordinarily this method stores bytes from the given array into this
   * stream's buffer, flushing the buffer to the underlying output stream as
   * needed.  If the requested length is at least as large as this stream's
   * buffer, however, then this method will flush the buffer and write the
   * bytes directly to the underlying output stream.  Thus redundant
   * <code>BufferedOutputStream</code>s will not copy data unnecessarily.
   *
   * @param b the data.
   * @param off the start offset in the data.
   * @param len the number of bytes to write.
   * @throws IOException if an I/O error occurs.
   */
  public synchronized void write(byte b[], int off, int len) throws IOException {
    if (len >= buf.length) {
            /* If the request length exceeds the size of the output buffer,
               flush the output buffer and then write the data directly.
               In this way buffered streams will cascade harmlessly. */
      flushBuffer();
      out.write(b, off, len);
      return;
    }
    if (len > buf.length - count) {
      flushBuffer();
    }
    System.arraycopy(b, off, buf, count, len);
    count += len;
  }

  /**
   * Flushes this buffered output stream. This forces any buffered
   * output bytes to be written out to the underlying output stream.
   *
   * @throws IOException if an I/O error occurs.
   * @see java.io.FilterOutputStream#out
   */
  public synchronized void flush() throws IOException {
    flushBuffer();
    out.flush();
  }
}
